Preparation method for diamines and polyamines of diphenylmethane series

Abstract

The present invention belongs to the technical field of preparation of diamines and polyamines of diphenylmethane series, and in particular to a preparation method for diamines and polyamines of diphenylmethane series (DAM). That is, before a condensation reaction, a mixing feature parameter of a pre-reaction solution for the condensation reaction is controlled to be 1.0 ≤ M ≤ 1.5; and the pre-reaction solution is a mixed solution formed by premixing a formaldehyde solution and aniline hydrochloride or by premixing the formaldehyde solution and a mixture of the aniline hydrochloride / a condensation reaction solution. In the method of the present invention, the mixing feature parameter M is controlled to be within a suitable range, which can reduce the content of N-methyl impurities and the content of macromolecule polymers in a DAM product to the greatest extent possible, and improve the operation stability of a production device and the quality of downstream products.

Description

Preparation method of diamines and polyamines of diphenylmethane series Technical Field

[0001] The invention belongs to the technical field of preparation of diphenylmethane series diamines and polyamines, and in particular relates to a preparation method of diphenylmethane series diamines and polyamines (DAM). Background Art

[0002] The diamines and polyamines of the diphenylmethane series (DAM for short) are understood to mean mixtures of the following types of diamines and polyamines:

[0003] Wherein, n represents a natural number ≥ 0.

[0004] The corresponding isocyanates which can be obtained formally by replacing all -NH2 groups in the compound of the structure shown in the above general formula with -NCO groups are respectively called diisocyanates and polyisocyanates of the diphenylmethane series (called MDI).

[0005] MDI is a key raw material in the polyurethane industry. The process of preparing polymethylene polyphenylamine (DAM) by reacting aniline and formaldehyde in the presence of an acid catalyst is well known in the industry. This DAM is then reacted with phosgene to synthesize MDI.

[0006] In the traditional DAM production process, formaldehyde undergoes a condensation reaction with aniline hydrochloride, or with a mixture containing a certain ratio of a condensation reaction product and aniline hydrochloride. This is followed by a transposition rearrangement reaction and neutralization reaction, and the oil phase product is finally refined to obtain the DAM product. As is well known in the art, the reaction between formaldehyde and aniline hydrochloride is a rapid reaction, occurring instantly upon contact between the raw materials and releasing a large amount of heat. Therefore, in industrial production, uneven formaldehyde dispersion in the pre-reaction solution is highly likely to occur, leading to localized excessive formaldehyde concentration and excessively high temperatures. This exacerbates condensation side reactions, resulting in increased N-methyl impurity and polymer content in DAM, affecting the long-term stable operation of the plant and increasing the hydrolyzed chlorine content in the downstream PMDI product, impacting product quality.

[0007] Patent document US8710267B2 discloses a method for preparing DAM from aminal, wherein an acidic catalyst is added to an aminal stream having a water content of <5%, and the input energy during the mixing process is preferably controlled to be >10kW / m 3 , more preferably >20kW / m 3 However, this condition is applicable to the mixing condition at 20-60°C, and this system is different from the mixing of aniline hydrochloride and formaldehyde solution. At the same time, the formaldehyde feed ratio and total feed load have not been studied, and the actual mixing effect cannot be guaranteed.

[0008] Patent document DE2049707A1 discloses a continuous method for preparing DAM. Aniline hydrochloride and formaldehyde are mixed in a rapid flow process, with the Reynolds number of the mixed materials controlled to 4500. The mixture then enters a tubular reactor for a condensation reaction. In this DAM preparation method, due to the presence of locally high formaldehyde concentrations during the mixing of aniline and formaldehyde, the majority of condensation side reactions occur during the premixing of the raw materials, while only a small portion of side reactions occur during the subsequent condensation reaction. The patent does not provide quantitative research on the premixing stage.

[0009] The mixing effect of aniline and formaldehyde directly affects the severity of the condensation side reaction. However, changes in production load, the ratio of aniline to formaldehyde, the condensation reaction temperature, etc. will also affect the rate of the condensation side reaction, thereby changing the mixing intensity requirements in the raw material premixing stage.

[0010] In view of this, how to effectively adjust or control the mixing effect of aniline and formaldehyde in the premixing stage so as to effectively reduce the N-methyl impurity content in DAM produced under different working conditions is a direction worthy of research.

[0011] Summary of the Invention

[0012] The premixing effect between formaldehyde solution and aniline hydrochloride or between formaldehyde solution and aniline hydrochloride / condensation reaction product mixture has a significant impact on the quality of the condensation reaction. As the mixing temperature, processing volume, and proportion of formaldehyde in the pre-reaction liquid increase during the premixing process, the demand for mixing intensity in the premixing stage will increase. Among them, the increase in mixing temperature has a particularly significant impact on the demand for mixing effect. Therefore, it is necessary to adjust the output power of the mixing device in a timely manner to enhance the mixing intensity between the materials. However, in actual operation, when a mixing device has been selected, it is not possible to further adjust the output power of the mixing device due to the limitations of the mixing equipment selection, or it is very difficult to adjust the output power of the mixing device.

[0013] In view of the above problems, the object of the present invention is to provide a method for preparing diphenylmethane series diamines and polyamines (DAM) with low content of side reaction impurities. The method can guide the production equipment to achieve effective mixing between formaldehyde and aniline hydrochloride or between formaldehyde and aniline hydrochloride / condensation reaction products under different operating conditions, thereby minimizing the N-methyl impurity content and macromolecular polymer content in the DAM product, improving the operational stability of the production equipment and the quality of downstream products.

[0014] In order to achieve the above object, the present invention provides the following technical solutions:

[0015] A method for preparing diphenylmethane series diamines and polyamines (DAM), wherein before the condensation reaction, the mixing characteristic parameter M of the pre-reaction liquid for the condensation reaction is controlled to be greater than or equal to 1.0, preferably greater than or equal to 1.0 and less than or equal to 1.5;

[0016] The pre-reaction liquid is a mixed liquid formed by premixing formaldehyde and aniline hydrochloride or a mixed liquid formed by premixing a mixture of formaldehyde and aniline hydrochloride / condensation reaction liquid;

[0017] The calculation formula of the hybrid characteristic parameter M is as follows:

[0018] Where,

[0019] n is the mass flow ratio of aniline hydrochloride to formaldehyde solution or the mass flow ratio of the mixture of aniline hydrochloride / condensation reaction liquid to formaldehyde solution;

[0020] P is the output power, in W;

[0021] V is the effective volume of the mixing device, m 3 ;

[0022] Q is the total feed flow rate of the mixed solution formed by formaldehyde solution and aniline hydrochloride or the total feed flow rate of the mixed solution formed by the mixture of formaldehyde solution and aniline hydrochloride / condensation reaction solution, in m 3 / h;

[0023] T is the mixing temperature in °C.

[0024] According to the preparation method provided by the present invention, in some embodiments, the preparation method comprises the following steps:

[0025] S1: contacting an aniline stream with a hydrochloric acid stream to generate a salt-forming reaction, thereby obtaining an aniline hydrochloride product stream;

[0026] S2: In a mixing device, premixing the aniline hydrochloride product stream obtained in step S1 with the formaldehyde solution to form a pre-reaction liquid; wherein a mixing characteristic parameter M of the pre-reaction liquid is controlled to be greater than or equal to 1.0 and less than or equal to 1.5 (for example, M is 1.1, 1.2, 1.3, 1.4, or 1.45);

[0027] Optionally, the pre-reaction liquid further includes a portion of the condensation reaction liquid obtained by the condensation reaction; that is, the aniline hydrochloride obtained in step S1 is mixed with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system; wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride can be, for example, (0-10):1, for example, 0.1:1, 0.2:1, 0.5:1, 0.8:1, 1:1, 2:1, 4:1, 5:1, 8:1, 9:1;

[0028] S3: The pre-reaction liquid obtained in step S2 is subjected to a condensation reaction to obtain a condensation reaction liquid; a portion of the condensation reaction liquid is returned to step S2 and mixed with the aniline hydrochloride product stream, and the remaining condensation reaction liquid is further subjected to a transposition rearrangement step, a neutralization step, and water washing to obtain a mixture of diamines and polyamines containing a diphenylmethane series;

[0029] S4: Purifying the mixture of diamines and polyamines containing the diphenylmethane series obtained in step S3, removing substances such as aniline and water in the system, and obtaining a DAM product.

[0030] In some embodiments, in step S1, the mass fraction of the solute in the hydrochloric acid stream is 25-37 wt% (e.g., 26 wt%, 28 wt%, 32 wt%, 34 wt%), preferably 30-35 wt%.

[0031] In some embodiments, in step S1, the molar ratio of HCl to aniline, calculated as the solute HCl in the hydrochloric acid stream, is 0.1-0.5 (e.g., 0.15:1, 0.22:1, 0.25:1, 0.3:1, 0.35:1, 0.42:1, 0.45:1, 0.48:1), preferably 0.2-0.4.

[0032] The salt-forming reaction may be a conventional operation in the art. In some embodiments, in step S1, the process conditions of the salt-forming reaction include: a reaction temperature of 20-55°C (e.g., 22°C, 25°C, 28°C, 33°C, 35°C, 38°C, 40°C, 45°C, 52°C), preferably 30-50°C; and a salt-forming reaction time of 5-60 min (e.g., 10 min, 20 min, 30 min, 40 min, 55 min), preferably 10-50 min.

[0033] In some embodiments, in step S2, the formaldehyde solution is in the form of an aqueous solution, and the mass fraction of the solute is 20-55wt% (for example, 25wt%, 30wt%, 35wt%, 37wt%, 40wt%, 44wt%, 50wt%, 52wt%), preferably 30-50wt%.

[0034] In some embodiments, in step S2, the molar ratio of formaldehyde to aniline, calculated as solute formaldehyde in the formaldehyde solution, is 0.2-0.8 (e.g., 0.22:1, 0.25:1, 0.28:1, 0.32:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.62:1, 0.65:1, 0.7:1, 0.75:1), preferably 0.3-0.6.

[0035] In some embodiments, in step S2, the mixing device is selected from at least one of a stirred tank and a homogenizing pump.

[0036] In some embodiments, the output power P of the stirred tank can be 15-45 kW (e.g., 16 kW, 18 kW, 20 kW, 22 kW, 25 kW, 28 kW, 30 kW, 35 kW, 40 kW, 42 kW).

[0037] In some embodiments, the output power P of the homogenizing pump can be 10-50 kW (eg, 12 kW, 15 kW, 16 kW, 18 kW, 20 kW, 22 kW, 25 kW, 28 kW, 30 kW, 35 kW, 40 kW, 42 kW, 45 kW, 48 kW).

[0038] In some embodiments, the applicable working conditions of the mixing characteristic parameter M are the working conditions of mixing formaldehyde solution with aniline hydrochloride, the working conditions of mixing formaldehyde solution with condensation reaction liquid, the working conditions of mixing aniline hydrochloride with condensation reaction liquid, and the working conditions of mixing formaldehyde solution with aniline hydrochloride and condensation reaction liquid.

[0039] In some embodiments, in the calculation formula of the mixing characteristic parameter M, the mixing temperature T is 30-105°C (e.g., 35°C, 40°C, 50°C, 80°C, 95°C), preferably 40-100°C.

[0040] In some embodiments, in the calculation formula of the mixing characteristic parameter M, the mass flow ratio n is (1-100):1, for example, 3:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 40:1, 50:1, 60:1, 80:1, 90:1, preferably (1-50):1, and more preferably (2-40):1.

[0041] In some embodiments, when a stirred tank is used as the premixing mixing device, the mass flow ratio n is preferably in the range of (10-40):1, for example, 12:1, 15:1, 20:1, 25:1, 30:1, 35:1.

[0042] In some embodiments, when a homogenizing pump is selected as the premixing mixing device, the mass flow ratio n is preferably in the range of (1-10):1, for example, 2:1, 4:1, 5:1, 6:1, 8:1.

[0043] In some embodiments, in the calculation formula of the mixing characteristic parameter M, the total feed flow rate Q is 1-1000m 3 / h, for example, 5m 3 / h、10m 3 / h、20m 3 / h、50m 3 / h、80m 3 / h、100m 3 / h、200m 3 / h、300m 3 / h、400m 3 / h、500m 3 / h、600m 3 / h、800m 3 / h、950m 3 / h, preferably 10-900m 3 / h.

[0044] In the calculation formula of the mixing characteristic parameter M, the effective volume V can be specifically determined according to the selected mixing device, and its specific range is not particularly limited.

[0045] In some embodiments, the mixing parameter M of the pre-reaction liquid is controlled to be greater than or equal to 1.0 and less than or equal to 1.5, and the N-methyl impurity content in the DAM product is below 0.2 wt % (for example, 0.18 wt % and below, 0.15 wt % and below, 0.12 wt % and below, 0.1 wt % and below, 0.08 wt % and below).

[0046] The condensation reaction can be a conventional operation in the art. According to the preparation method of the present invention, in some embodiments, in step S3, the process conditions of the condensation reaction include: a reaction temperature of 40-100°C (for example, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C), preferably 45-95°C; and a reaction residence time of, for example, 0.1h-1h (for example, 0.2h, 0.4h, 0.5h, 0.8h).

[0047] In step S3, the transposition rearrangement process can be a conventional operation in the art. For example, its process conditions include: a reaction temperature of 100-150°C, for example, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C; a reaction residence time of 0.5-5h, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h.

[0048] In step S3, the neutralization process and the water washing process are conventional operations in the art and can be implemented with reference to the existing technology. The present invention has no particular limitations.

[0049] In step S4, the refining process is a conventional operation in the art and can be implemented with reference to the existing technology. The present invention has no particular limitation. In the art, water and solvent are usually removed by resin adsorption or distillation, and the distillation is preferably vacuum distillation.

[0050] The inventors of the present invention have discovered through research that by controlling the mixing characteristic parameter M of the pre-reaction liquid (formed by pre-mixing formaldehyde solution and aniline hydrochloride or pre-mixing formaldehyde solution and aniline hydrochloride / condensation reaction product), the occurrence of condensation side reactions in the condensation process can be greatly reduced; when the value of the mixing characteristic parameter M is greater than 1, it can be ensured that the raw materials in the pre-mixing stage obtain sufficient mixing intensity, thereby reducing the occurrence of condensation side reactions in the pre-mixing stage, so that the N-methyl impurity content in the DAM product stream obtained under different working conditions is effectively controlled, avoiding an increase in the hydrolysis chlorine content in the downstream product PM, and suppressing the content of macromolecular polymers in the condensation device, thereby ensuring long-term stable operation of the device. In addition, the mixing characteristic parameter M of the pre-reaction liquid in the present invention can be flexibly regulated by a variety of factors (such as the mass flow rate ratio of formaldehyde to aniline hydrochloride or the mass flow rate ratio n of the mixture of formaldehyde and aniline hydrochloride / condensation reaction liquid, the output power P of the mixing device, the total feed flow rate Q during the premixing process, the mixing temperature T, etc.), so that the regulation of the mixing characteristic parameter M is flexible and convenient, and will not be restricted by factors such as device selection.

[0051] Compared with the prior art, the beneficial effect of the technical solution of the present invention is at least that: the method of the present invention can flexibly regulate the mixing characteristic parameter M of the pre-reaction liquid through multiple factors, and control the mixing characteristic parameter M within an appropriate range (such as 1.0≤M≤1.5), which can improve the reaction quality and the quality of the obtained product, control the N-methyl impurity content in DAM to <0.2%, and effectively alleviate the polymer blockage during the operation cycle of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG1 shows a schematic process flow diagram of a method for preparing DAM in some embodiments of the present invention.

[0053] In Figure 1, the reference numerals are explained as follows: 1 - mixer; 2 - heat exchanger; 3 - stirring tank; 4 - reactor.

[0054] FIG2 shows a schematic process flow diagram of a method for preparing DAM in some embodiments of the present invention.

[0055] In FIG2 , the reference numerals are described as follows: 1-mixer; 2-heat exchanger; 3'-homogenizing pump; 4-reactor. DETAILED DESCRIPTION

[0056] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0057] Unless otherwise specified, the experimental procedures used in the following examples are conventional methods.

[0058] <Source of raw materials>

[0059] Aniline stream: provided by Ningbo Wanhua Industrial Park, concentration is 99.9wt%;

[0060] Hydrochloric acid stream: provided by Ningbo Wanhua Industrial Park, concentration is 33wt%;

[0061] Formaldehyde stream: provided by Ningbo Wanhua Industrial Park, concentration is 37wt%;

[0062] Sodium hydroxide aqueous solution: provided by Ningbo Wanhua Industrial Park, concentration is 50wt%.

[0063] <Test Method>

[0064] The determination method of each component in the DAM obtained in each embodiment and comparative example was carried out by liquid chromatography, and the analytical instrument was Agilent 1200.

[0065] Example 1

[0066] The preparation process of diamines and polyamines of the diphenylmethane series, as shown in Figure 1, includes the following steps:

[0067] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.25:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 35° C., and the reaction time is 20 min;

[0068] S2. Mixing the aniline hydrochloride obtained in step S1 with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system, wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride is 8.2:1, to form a mixture of aniline hydrochloride / condensation reaction liquid; transferring heat from the mixture of aniline hydrochloride / condensation reaction liquid through a heat exchanger 2, controlling the temperature of the stirred tank 3 to 50° C., and then introducing the mixture of aniline hydrochloride / condensation reaction liquid and the formaldehyde solution into the stirred tank 3 at this temperature for rapid premixing, wherein the mass flow ratio n of the mixture of aniline hydrochloride / condensation reaction liquid to the formaldehyde solution is 30:1, and the total feed flow rate Q of the mixed solution formed by the formaldehyde solution and the mixture of aniline hydrochloride / condensation reaction liquid in the stirred tank 3 is 850 m3 / s. 3 / h, the output power in the stirring tank 3 is 45000W, and the effective volume V of the stirring tank 3 is 0.20m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 1.11;

[0069] S3, the pre-reaction liquid obtained in step S2 is introduced into the reactor 4 for condensation reaction, the condensation reaction temperature is 60 ° C, and the residence time is 0.5h; a portion of the obtained condensation reaction product (condensation reaction liquid) is returned to the discharge pipe of the mixer 1 and mixed with aniline hydrochloride, and the remaining condensation reaction product (condensation reaction liquid) is introduced into the subsequent device to continue the transposition rearrangement process, the neutralization process, and the washing to obtain a mixture of diamines and polyamines containing diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 120 ° C, and the transposition rearrangement reaction time is 2h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100 ° C, and the reaction time is 10min;

[0070] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0071] The prepared DAM had a dicyclic substance (diamine) content of 60.1 wt %, an N-methyl impurity content of 0.17 wt %, and a macromolecular polymer (polyamine containing ten or more benzene rings) content in the condensation reaction device of 78 ppm.

[0072] Example 2

[0073] The preparation process of diamines and polyamines of the diphenylmethane series, as shown in Figure 1, includes the following steps:

[0074] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.30:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 35° C., and the reaction time is 20 min;

[0075] S2. Mixing the aniline hydrochloride obtained in step S1 with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system, wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride is 3.1:1, to form a mixture of aniline hydrochloride / condensation reaction liquid; transferring heat from the mixture of aniline hydrochloride / condensation reaction liquid through a heat exchanger 2, controlling the temperature of the stirred tank 3 to 45° C., and then introducing the mixture of aniline hydrochloride / condensation reaction liquid and the formaldehyde solution into the stirred tank 3 at this temperature for rapid premixing, wherein the mass flow ratio n of the mixture of aniline hydrochloride / condensation reaction liquid to the formaldehyde solution is 14:1, and the total feed flow rate Q of the mixed solution formed by the formaldehyde solution and the mixture of aniline hydrochloride / condensation reaction liquid in the stirred tank 3 is 400 m3 / s. 3 / h, the output power in the stirring tank 3 is 18000W, and the effective volume V of the stirring tank 3 is 0.09m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 1.14;

[0076] S3, the pre-reaction liquid obtained in step S2 is introduced into the reactor 4 for condensation reaction, the condensation reaction temperature is 50 ° C, and the residence time is 0.5h; a portion of the obtained condensation reaction product (condensation reaction liquid) is returned to the discharge pipe of the mixer 1 and mixed with aniline hydrochloride, and the remaining condensation reaction product (condensation reaction liquid) is introduced into the subsequent device to continue the transposition rearrangement process, the neutralization process, and the washing process to obtain a mixture of diamines and polyamines containing diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 130 ° C, and the transposition rearrangement reaction time is 2h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100 ° C, and the reaction time is 10min;

[0077] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0078] The prepared DAM had a dicyclic substance (diamine) content of 60.6 wt %, an N-methyl impurity content of 0.15 wt %, and a macromolecular polymer (polyamine containing more than ten benzene rings) content in the condensation reaction device of 75 ppm.

[0079] Example 3

[0080] The preparation process of diphenylmethane series diamines and polyamines, as shown in Figure 2, includes the following steps:

[0081] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.21:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 40° C., and the reaction time is 20 min;

[0082] S2. Mixing the aniline hydrochloride obtained in step S1 with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system, wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride is 0.9:1, to form a mixture of aniline hydrochloride / condensation reaction liquid; the mixture of aniline hydrochloride / condensation reaction liquid is passed through a heat exchanger 2 for heat transfer, and the temperature of the homogenizing pump 3' is controlled to be 95° C., and then at this temperature, the mixture is passed into the homogenizing pump 3' with the formaldehyde solution for rapid premixing, wherein the mass flow ratio n of the mixture of aniline hydrochloride / condensation reaction liquid to the formaldehyde solution is 6:1, and the total feed flow Q of the mixed solution formed by the mixture of formaldehyde solution and aniline hydrochloride / condensation reaction liquid in the homogenizing pump 3' is 100 m 3 / h, the output power of the homogenizing pump 3' is 30000W, and the effective volume V of the homogenizing pump 3' is 0.05m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 1.46;

[0083] S3, the pre-reaction liquid obtained in step S2 is introduced into the reactor 4 for condensation reaction, the condensation reaction temperature is 95 ° C, and the residence time is 0.5h; a portion of the obtained condensation reaction product (condensation reaction liquid) is returned to the discharge pipe of the mixer 1 and mixed with aniline hydrochloride, and the remaining condensation reaction product (condensation reaction liquid) is introduced into the subsequent device to continue the transposition rearrangement process, the neutralization process, and the water washing to obtain a mixture of diamines and polyamines containing diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 140 ° C, and the transposition rearrangement reaction time is 2h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100 ° C, and the reaction time is 10min;

[0084] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0085] The prepared DAM had a dicyclic substance (diamine) content of 55.6 wt %, an N-methyl impurity content of 0.18 wt %, and a macromolecular polymer (polyamine containing ten or more benzene rings) content in the condensation reaction device of 97 ppm.

[0086] Example 4

[0087] The preparation process of diphenylmethane series diamines and polyamines, as shown in Figure 2, includes the following steps:

[0088] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.13:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 40° C., and the reaction time is 10 min;

[0089] S2. The aniline hydrochloride prepared in step S1 is passed through the heat exchanger 2 for heat transfer. The temperature of the homogenizing pump 3' is controlled to 85°C. At this temperature, the aniline hydrochloride and the formaldehyde solution are introduced into the homogenizing pump 3' for rapid premixing. The mass flow ratio n of the aniline hydrochloride to the formaldehyde solution is 2.9:1, and the total feed flow rate Q of the mixed solution formed by the formaldehyde solution and the aniline hydrochloride in the homogenizing pump 3' is 40m 3 / h, the output power of the homogenizing pump 3' is 10000W, and the effective volume V of the homogenizing pump 3' is 0.05m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 1.33;

[0090] S3, the pre-reaction liquid obtained in step S2 is introduced into reactor 4 for condensation reaction, the condensation reaction temperature is 85° C., and the residence time is 0.5 h; the obtained condensation reaction product (condensation reaction liquid) is introduced into a subsequent device to continue the transposition rearrangement process, the neutralization process, and the water washing to obtain a mixture of diamines and polyamines containing a diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 110° C., and the transposition rearrangement reaction time is 2 h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100° C., and the reaction time is 10 min;

[0091] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0092] The prepared DAM had a dicyclic substance (diamine) content of 57.2 wt %, an N-methyl impurity content of 0.16 wt %, and a macromolecular polymer (polyamine containing ten or more benzene rings) content in the condensation reaction device of 82 ppm.

[0093] Example 5

[0094] The preparation process of diphenylmethane series diamines and polyamines, as shown in Figure 2, includes the following steps:

[0095] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.37:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 40° C., and the reaction time is 10 min;

[0096] S2. Mixing the aniline hydrochloride obtained in step S1 with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system, wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride is 1.8:1, to form a mixture of aniline hydrochloride / condensation reaction liquid; the mixture of aniline hydrochloride / condensation reaction liquid is passed through a heat exchanger 2 for heat transfer, and the temperature of the homogenizing pump 3' is controlled to be 75° C., and then at this temperature, the mixture is passed into the homogenizing pump 3' with the formaldehyde solution for rapid premixing, wherein the mass flow ratio n of the mixture of aniline hydrochloride / condensation reaction liquid to the formaldehyde solution is 10:1, and the total feed flow Q of the mixed solution formed by the formaldehyde solution and the mixture of aniline hydrochloride / condensation reaction liquid in the homogenizing pump 3' is 300 m3 / s. 3 / h, the output power of the homogenizing pump 3' is 50000W, and the effective volume V of the homogenizing pump 3' is 0.05m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 1.28;

[0097] S3, the pre-reaction liquid obtained in step S2 is introduced into the reactor 4 for condensation reaction, the condensation reaction temperature is 75 ° C, and the residence time is 0.5h; a portion of the obtained condensation reaction product (condensation reaction liquid) is returned to the discharge pipe of the mixer 1 and mixed with aniline hydrochloride, and the remaining condensation reaction product (condensation reaction liquid) is introduced into the subsequent device to continue the transposition rearrangement process, the neutralization process, and the water washing to obtain a mixture of diamines and polyamines containing diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 105 ° C, and the transposition rearrangement reaction time is 2h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100 ° C, and the reaction time is 10min;

[0098] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0099] The prepared DAM had a dicyclic substance (diamine) content of 58.4 wt %, an N-methyl impurity content of 0.15 wt %, and a macromolecular polymer (polyamine containing more than ten benzene rings) content in the condensation reaction device of 72 ppm.

[0100] Comparative Example 1

[0101] The preparation process of diamines and polyamines of the diphenylmethane series, as shown in Figure 1, includes the following steps:

[0102] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.25:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 35° C., and the reaction time is 20 min;

[0103] S2. Mixing the aniline hydrochloride obtained in step S1 with a portion of the condensation reaction product (condensation reaction liquid) circulating in the system, wherein the mass flow ratio of the circulating condensation reaction liquid to the aniline hydrochloride is 9:1, to form a mixture of aniline hydrochloride / condensation reaction liquid; transferring heat from the mixture of aniline hydrochloride / condensation reaction liquid through a heat exchanger 2, controlling the temperature of the stirred tank 3 to be 65° C., and then introducing the mixture of aniline hydrochloride / condensation reaction liquid and the formaldehyde solution into the stirred tank 3 at this temperature for rapid premixing, wherein the mass flow ratio n of the mixture of aniline hydrochloride / condensation reaction liquid to the formaldehyde solution is 31:1, and the total feed flow rate Q of the mixed solution formed by the formaldehyde solution and the mixture of aniline hydrochloride / condensation reaction liquid in the stirred tank 3 is 800 m3 / s. 3 / h, the output power in the stirring tank 3 is 30000W, and the effective volume V of the stirring tank 3 is 0.25m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 0.78;

[0104] S3, the pre-reaction liquid obtained in step S2 is introduced into the reactor 4 for condensation reaction, the condensation reaction temperature is 60 ° C, and the residence time is 0.5h; a portion of the obtained condensation reaction product (condensation reaction liquid) is returned to the discharge pipe of the mixer 1 and mixed with aniline hydrochloride, and the remaining condensation reaction product (condensation reaction liquid) is introduced into the subsequent device to continue the transposition rearrangement process, the neutralization process, and the washing process to obtain a mixture of diamines and polyamines containing diphenylmethane series; wherein: the reaction temperature of the transposition rearrangement process is 120 ° C, and the transposition rearrangement reaction time is 2h; the neutralization process adopts sodium hydroxide aqueous solution (concentration 50wt%) for neutralization, the molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100 ° C, and the reaction time is 10min;

[0105] S4: The mixture of diamines and polyamines containing diphenylmethane series obtained in step S3 is refined, and aniline and water are removed therefrom by vacuum distillation to finally obtain DAM product; wherein the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0106] The prepared DAM had a dicyclic substance (diamine) content of 57.9 wt%, an N-methyl impurity content of 0.24 wt%, and a macromolecular polymer (polyamine containing ten or more benzene rings) content in the condensation reaction device of 132 ppm. Compared with Example 1, the operating cycle of the entire device was shortened by 19%.

[0107] Comparative Example 2

[0108] The preparation process of diphenylmethane series diamines and polyamines, as shown in Figure 2, includes the following steps:

[0109] S1. Adding a 33 wt % hydrochloric acid stream and a 99.99 wt % aniline stream into a mixer 1 at a molar ratio of HCl to aniline of 0.13:1, mixing and reacting the mixture to produce aniline hydrochloride; the reaction temperature is 40° C., and the reaction time is 10 min;

[0110] S2. The aniline hydrochloride prepared in step S1 is passed through the heat exchanger 2 for heat transfer. The temperature of the homogenizing pump 3' is controlled to 75°C. At this temperature, the aniline hydrochloride and the formaldehyde solution are introduced into the homogenizing pump 3' for rapid premixing. The mass flow ratio n of the aniline hydrochloride and the formaldehyde solution is 3.1:1. The total feed flow rate Q of the mixed solution formed by the formaldehyde solution and the aniline hydrochloride in the homogenizing pump 3' is 150m 3 / h, the output power of the homogenizing pump 3' is 50000W, and the effective volume V of the homogenizing pump 3' is 0.05m 3 , at this time, the mixing characteristic parameter M of the premixed liquid formed by premixing is 0.79;

[0111] S3. Feed the pre-reaction solution obtained in step S2 into the reaction kettle 4 for condensation reaction. The condensation reaction temperature is 85°C and the residence time is 0.5 h. The obtained condensation reaction product (condensation reaction solution) enters the subsequent device to continue the transposition rearrangement process, neutralization process, and water washing to obtain a mixture containing diamines and polyamines of the diphenylmethane series. Among them: the reaction temperature of the transposition rearrangement process is 110°C and the transposition rearrangement reaction time is 2 h; the neutralization process is carried out with an aqueous sodium hydroxide solution (concentration 50 wt%) for neutralization. The molar ratio of sodium hydroxide to hydrochloric acid (calculated as HCl) is 1.1, the reaction temperature is 100°C, and the reaction time is 10 min.

[0112] S4: Refine the mixture containing diamines and polyamines of the diphenylmethane series obtained in step S3, and remove aniline and water therein by vacuum distillation to finally obtain the DAM product. Among them, the operating pressure of the vacuum distillation is 1 kPa and the operating temperature is 220°C.

[0113] In the prepared DAM, the content of the bicyclic substance (diamine) is 55.0 wt%, the content of N-methyl impurities is 0.25 wt%, and the content of macromolecular polymers (polyamines with more than ten benzene rings) in the condensation reaction device is 152 ppm. Compared with Example 4, the operation cycle of the entire device is shortened by 23%.

[0114] Table 1 Process conditions in the pre-mixing stage of each example and comparative example

[0115] As can be seen from the results of the above examples and comparative examples, the present invention provides a method for preparing diamines and polyamines (DAM) of the diphenylmethane series. By controlling the mixing characteristic parameter 1 < M < 1.5 of the pre-reaction solution of the condensation reaction, the reaction of aniline and formaldehyde can be effectively improved and the quality of the obtained product DAM can be improved, and the content of N-methyl impurities in DAM can be controlled < 0.2%, and at the same time, the content of macromolecular polymers can be effectively reduced (< 100 ppm), which can significantly extend the stable operation cycle of the production device.

[0116] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the method of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing diphenylmethane series diamines and polyamines, characterized in that, Before the condensation reaction, control the mixing characteristic parameter M of the pre-reaction liquid for the condensation reaction to be greater than or equal to 1.0, preferably M is greater than or equal to 1.0 and less than or equal to 1.5; The pre-reaction liquid is a mixed liquid formed after premixing formaldehyde and aniline hydrochloride or a mixed liquid formed after premixing a mixture of formaldehyde and aniline hydrochloride / condensation reaction liquid; The calculation formula of the mixed feature parameter M is as follows: In the formula, n is the mass flow ratio of aniline hydrochloride to formaldehyde solution or the mass flow ratio of a mixture of aniline hydrochloride / condensation reaction liquid to formaldehyde solution; P is the output power, with the unit of W; V is the effective volume of the mixing device, m 3 ; Q is the total feed flow rate of the mixed solution formed by the formaldehyde solution and the aniline hydrochloride, or the total feed flow rate of the mixed solution formed by the formaldehyde solution and the mixture of aniline hydrochloride / condensation reaction solution, with the unit of m 3 / h; T is the mixing temperature, with the unit of °C.

2. The preparation method according to claim 1, characterized in that, This preparation method includes the following steps: S1: Contact the aniline feed stream with the hydrochloric acid feed stream to carry out a salt formation reaction to obtain an aniline hydrochloride product stream; S2: In a mixing device, premix the aniline hydrochloride product stream obtained in step S1 with a formaldehyde solution to form a pre-reaction liquid; wherein, control the mixing characteristic parameter M of the pre-reaction liquid to be greater than or equal to 1.0 and less than or equal to 1.5; Optionally, the pre-reaction liquid also includes a part of the condensation reaction liquid obtained from the condensation reaction; S3: After the pre-reaction liquid obtained in step S2 undergoes a condensation reaction, a condensation reaction liquid is obtained; a part of the condensation reaction liquid is returned to step S2 and mixed with the aniline hydrochloride product stream mix, and the remaining condensation reaction liquid continues to be subjected to a rearrangement process, a neutralization process, and a water wash to obtain a mixture containing diamines and polyamines of the diphenylmethane series; S4: Refine the mixture containing diamines and polyamines of the diphenylmethane series obtained in step S3 to obtain a DAM product.

3. The preparation method according to claim 2, wherein, In step S1, the mass fraction of the solute in the hydrochloric acid feed stream is 25 - 37 wt%, preferably 30 - 35 wt%; and / or Based on HCl in the solute of the hydrochloric acid feed stream, the molar ratio of HCl to aniline is 0.1 - 0.5, preferably 0.2 - 0.

4.

4. The preparation method according to claim 2 or 3, characterized in that, In step S2, the formaldehyde solution exists in the form of an aqueous solution, and the mass fraction of its solute is 20 - 55 wt%, preferably 30 - 50 wt%.

5. The preparation method according to any one of claims 2-4, characterized in that, In step S2, the mixing device is selected from at least one of a stirring kettle and a homogenizing pump.

6. The preparation method according to any one of claims 1-5, characterized in that, The applicable working conditions of the mixing characteristic parameter M are the working conditions for mixing formaldehyde solution and aniline hydrochloride, the working conditions for mixing formaldehyde solution and condensation reaction liquid, the working conditions for mixing aniline hydrochloride and condensation reaction liquid, and the working conditions for mixing formaldehyde solution with aniline hydrochloride and condensation reaction liquid.

7. The preparation method according to any one of claims 1-6, characterized in that, In the calculation formula of the mixing characteristic parameter M, the mixing temperature T is 30 - 105 °C, preferably 40 - 100 °C.

8. The preparation method according to any one of claims 1-7, characterized in that, In the calculation formula of the mixing characteristic parameter M, the mass flow ratio n is (1 - 100):1, preferably (1 - 50):1, more preferably (2 - 40):1; Preferably, when the mixing device for premixing is a stirring kettle, the mass flow ratio n is (10 - 40):1; Preferably, when the mixing device for premixing is a homogenizing pump, the mass flow ratio n is (1 - 10):

1.

9. The preparation method according to any one of claims 1-8, characterized in that, In the calculation formula of the mixed characteristic parameter M, the total feed flow rate Q is 1 - 1000 m 3 / h, preferably 10 - 900 m 3 / h.

10. The preparation method according to any one of claims 1-9, characterized in that, Control the mixing parameter M of the pre-reaction liquid to be greater than or equal to 1.0 and less than or equal to 1.5, and the content of N-methyl impurities in the DAM product is below 0.2 wt%.

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